Apparatus for electrically coating the bore of carbon brushes for attaching the lead wire with metal



May 2, 1933. Y. UEK] LLY COATING THE BORE OF CARE APPARATUS FOR ELECTRICA BRUSHES FOR .ATTACHING THE LEAD WIRE WITH METAL Filed April 25. 1931 0000 I 0000 0 0 n0 0 0n0 0 0 0 0 0 0 v0 0 0( 0 0 *0 0 0 0 0 0 0 0 0 0 0 0 0 b P v...) Q Q Q QQOOQQQQQQQOOQO I Jaye/2X07: sfil ola Zll Patented May 2, 1933 UNITED STATES PATENT OFFICE,

YOSHIGORO UEKI, F EBABA GUNZTOKYO, JAPAN APPARATUS FOR ELECTRICALLY COATING THE B03150! CARBON BRUSHES FOR ATTACHING THE LEAD WIRE WITH METAL Application filed April 25, 1981, Serial No. 532,882, and in Japan Kay 8, 1930.

The present invention relates to improve- 7 ments in a method-and apparatus for electrically coating with metal the bore into which a lead wire is to be secured in carbon brushes and the like. In copper coating the bore,

electrically, accordin to the present invention, thin rubber or li eplates of height and width equal to the carbon brushes, and provided with electrodes at the portions corre- 1 spondin to the bore of brushes, are alternately plled in series with the carbon brushes and tightly clamped together. This forms baths at the bore of the carbon brushes, in which bores an electrical coating is desired.

The object of the invention is to electrically coat the bore of carbon brushes, without dipping the same in an electric plating bath. Another object of the invention is to avoid the change of brush size, when metal plated 90 at unuseful portions. A further object of the invention is to perfectly coat the bore with copper, without affecting the quality of the brush, and to reduce electric reslstance at .the portion where the lead wire is to be fitted.

Hitherto, it has been common to copperplate the bore of carbon brushes to reduce electric resistance at the contact part ofthe lead wire; the upper part of the carbon brush being dipped into an electrolytic bath for electrically coating the inner surface of the lead wire receiving bore. According to said process, the brush is inevitably coated also on parts other than the bore, the size of the brush being thereby changed, so that this process is inapplicable in cases where the allowable difference in the size of brushes is restricted, for instance, within five thousandths of an inch. It has also been proposed to coat brushes with paraffin or the like, on parts other than the bore, to prevent metal from being coated thereon. However, the nature of the brush is considerably affected by said paraffin coat ing and a rather harmful effect is induced thereby. I

According to the present invention, the bore of carbon brushes can be perfectly coated with metal without chan 'ng the size or affecting the nature of the rush. The invention is characterized in that the bore itself constitutes the electric bath, and only the lead 'wire receiving bore may be perfectly coated with metal easily and rapidly.

The invention is fully described with reference to the accompanying drawing in which: Figure 1 is a vertical sectional view of the lmproved apparatus showing the bores filled with solution, for carrying out the process,

Figure 2 is an elevation showing a rubber plate provided with an electrode .at its top, and adapted to be alternately piled in a se ries with the brushes, and

Figures 3, 4 and 5 show,--in bracketed arrangement, elevations and side views, respectively, ofvarious forms 'of bores formed in brushes.

The same reference characters designate corresponding parts throughout the drawing.

Referring now to the apparatus of Figure 1, wherein several brushes are shown havin their bores filled with coating solution, designates the carbon brushes to be treated,

I and 2 designates feed wires connected to a generator, or other source of electricity. 3 designates copper electrodes connected to the positive terminal of the generator. 5 designates rubber, cork or simllar plates provided with copper electrodes 3 and copper washers 9. 6 designates a screw bolt for tightenin the runner plates closel to the brushes alternately piled in a series with the plates 5. 8 designates the bores formed at: the upper part of the brushes C, for attaching the lead wire therein, and filled with coating solution Q for carrying out the process. v Fig. 2 shows in elevation a rubber plate 5. At the upper edge of said rubber plates a copper electrode 3 is inserted and copper washers are attached at both sides, through the centre of which apertures 4 are formed for passage of the coating solution.

Figs. 3, 4 and 5 show various forms of bores for attaching lead wires, a as front elevations and b as side elevations. 8 designates the bores for fitting the lead wire therein and 11 the recesses for receiving the washers. Said bores and recesses are filled with coating solution.

In carrying out the invention carbon brushes finished to a desired size are alter- 0 nately piled in series with rubber plates 5, keeping the bores in line, and the screw bolt 6 rotated to tightly compress the whole together. In the recesses formed by the bores of the brushes, forming plating baths, is

poured a solution containing pure copper sulphate 453 grms, sulphuric acid 23 grms., zinc acetate '23 grins. and'pure water 9 litres. Keeping the temperature of the solution at -10 20 to 40 C. an electric current of 1 to 3.2

volts is passed at the rate of 0.8 to 2.4 amperes per square millimetre of the coating surface. The current is held for about 10 minutes, whereby a copper coating of two thousandths to three thousandths of an inch thick is obtained inside the bore.

When the lead wire is fitted in. the bore of the brush, as treated above, it is kept in close contact therein and electric resistance at said contact part'is reduced from one half to one third, as compared with those not coated with metal in the bore. The treatment may be easily and rapidly performed without affecting the size and quality of the carbon brush. I declare that what I claim is An apparatus for electroplating carbon articles, comprising means to press together a number of stacked carbon articles, insulating members disposed between each carbon article of the pressed stack, a connector associated with each insulating member and extending on a portion of two sides of this member flush with the surface thereof, and an electric current source suitably connected to the carbon pack and the connectors, whereby an electrol tic liquid introduced in cavities of the carbon articles and in contact with the extending portions of the connectors is decomposed and caused to deposit a layer of metal inside the said cavities of the carbon articles.

In testimony wherefor I have affixed signature.

YOSHIGORO UEKI. 

